In primary school mathematics, if you want to draw a line segment first, you must first make clear the starting point of the line segment, and then draw a line with a ruler to judge the length at a clear end.
An edge of a graph is a line segment around the graph. In fact, it is the line segment related to the calculation of perimeter that we have learned in mathematical concepts. For example, the outermost line of a square is its sideline, that is, the line segment around it.
straight line
Made up of countless points. A straight line is a part of a surface and then constitutes a body. There is no end point, extending to both ends indefinitely, and the length cannot be measured. A straight line is an axisymmetric figure.
It has countless axes of symmetry, one of which is itself, and all lines perpendicular to it (there are countless axes of symmetry). There is only one straight line between two non-overlapping points on the plane, that is, two non-overlapping points determine a straight line. On the sphere, countless similar straight lines can be made after two points.